Radio observations of early-type galaxies with dust lanes

Abstract

Radio and optical images of early-type galaxies with dust lanes have been analyzed in order to investigate the characteristics of the radio emission and to compare it with their properties at other frequencies. Except three galaxies, the remaining sources of our sample have diffuse radio emission, which does not extend beyond the stellar disk. The radio structures are small and weak (linear sizes in the range 2–10 kpc and radio powers in the range 5×10²⁰–5×10²¹W Hz⁻¹). Our preliminary results show that in a minority of cases (the most powerful radio sources) radio emission originates in the associated galactic nuclei, where a massive black hole is harboured. On the contrary, in the less powerful among our radio galaxies, sources originating from stellar phenomena may play and important role. We have classified the galaxies with respect to the dust lane morphology, comparing it with the radio emission. The sample is too small in order to reach firm conclusions, but the lack of radio sources in early-type galaxies with dust lanes along the galaxy minor axis seems to suggest that the accretion of material does not reach the conditions necessary to trigger nuclear activity.